MC7 better understanding

I purchased MC7 about a month ago and put it into my laptop (MBP i7 Retina 2.3 model) and have been learning the software via Avid LEarning Series books.

What I noticed from the very beginning is when I opened the software a notice said "no media files can be written, please check permissions". But once I plugged in my external HD it never came out so I assumed everything was being written there.

So I just have some general questions I'm sure you guys can easily answer and would be such a big help to me.

1) the Avid learning Series required that I dump its tutorial files folder on my desktop. So it's just sitting there then I plug in my external HD and start the tutorial and everything works fine. I'm basically just a little confused and I want a better grasp on What's basically going on in my system, what is being written where or stored where, or which is running off of what

AND --

2) -- is this current setup ideal? What would you recommend?

- I have 2 external HDs. A Lacie 1TB thunderbolt series and a Seagate 1TB usb 3.0.

Please I'm open to any comments and suggestions! MANY THANKS IN ADVANCE!

Re: MC7 better understanding

1) By default your main OS drive is protected from having media written to it. It's an option in the preferences that's defaulted to on. Leave it on. Always work with external hard drives when using edit systems. They are larger, and are better suited for media storage.

2) The ideal solution is a computer and an external drive fast enough to handle media. USB3, Firewire 800, Thunderbolt. A second monitor gives you more room to work from. And then a video IO solution to view your image full screen on an external HDTV or broadcast monitor. But you don't NEED all that..it's just ideal. All you need is the laptop and hard drive. A second computer display is helpful though...more room. And if you are doing the finishing, and by that I mean what you are outputting will be the final...best to know what your video really looks like on an HDTV, since the Avid interface is far from accurate.